Lateral positioning of moving fibrous materials

ABSTRACT

A process and apparatus are provided for laterally positioning at a relatively fixed location a continuous length of fibrous material which is moving substantially in the direction of its length and which is free to undergo lateral movement. The fibrous material possesses a twist of at least about 0.1 tpi, and preferably comprises a plurality of parallel twisted multifilament fiber bundles which are in the form of a ribbon. The lateral position of the fibrous material is sensed and its relatively fixed location is maintained through contact (e.g. tangential contact) with a variably rotating roller.

United States Patent Ram 1451 Dec. 12, 1972 [54] LATERAL POSITIONING OF MOVING FIBROUS MATERIALS [72] Inventor: Michael J. Ram, West Orange, NJ.

[73] Assignee: Celanese Corporation, New York,

22] Filed: Aug. 4, 1971 211 Appl. 110.; 168,879

[52] US. Cl ..226/3, 226/16 [51] Int. Cl. ..B65h 25/26 [58] Field of Search ..'.226/3, 15, 16; 57/58.83, 90, 57/91; 19/65 T [56] References Cited UNITED STATES PATENTS 11 /1940 Stockbarger ..226/l6 x Primary Examiner-Richard A. Schacher Attorney--Thomas J. Morgan et a1.

[57] ABSTRACT A process and apparatus are provided for laterally positioning at a relatively fixed location a continuous length of fibrous material which is moving substan tially in the direction of its length and which is free to undergo lateral movement. The fibrous material possesses a twist of at least about 0.1 tpi, and preferably comprises a plurality of parallel twisted multifilament fiber bundles which are in the form of a ribbon. The lateral position of the fibrous material is sensed and its relatively fixed location is maintained through contact (e.g. tangential contact) with a variably rotating roller.

10 Claims, 3 Drawing Figures 4/1966 Gowin ..226/l5 X PATENTED Mn 12 1912 INVENTOR, Mama J P4 LATERAL POSITIONING OF MOVING FIBROUS MATERIALS BACKGROUND OF THE INVENTION In many areas of fiber technology the need arises for an efficient means to control the lateral position of a continuous length of moving fibrous material. Such need is of particular importance when the moving fibrous material traverses an appreciable distance and must be accurately positioned when undergoing intermediate processing and/or take-up.

While it is possible to control the lateral position of moving length of fibrous material by the use of fixed guides positioned along its path, contact with such guides may result in a diminution of the singlefilament tensile properties of the fibrous material as it contacts the guides. For instance, the tensile strength and modulus of many inorganic fibrous materials, such as carbonaceous fibrous materials, are reduced if substantial contact is made with a fixed guide. Also, if the moving fibrous material is in the form of a flat tape consisting of a plurality of adjoining parallel fibrous bundles, rather than a single fibrous'bundle, then there is a tendency for the fibrous bundles to become bunched or for the tape to fold upon itself when a fixed guide is contacted, thereby destroying its otherwise fiat configuration. When such folding occurs, the uniform intermediate processing and/or take-up of the same becomes difficult if not impossible. Curved bars have also sometimes been used to laterally position a plurality of fibrous bundles; however, there is once again a tendency for the bundle density to be rendered nonuniform, i.e. to increase at the center of the bar.

It is an object of the invention to provide an improved process for laterally positioning at a relatively fixed location a continuous length of moving fibrous material.

It is an object of the invention to provide an apparatus capable of laterally positioning at a relatively fixed location a continuous length of fibrous material which is moving substantially in the direction of its length.

It is an object of the invention to provide an improved technique for the lateral positioning of a continuous length of moving fibrous material at a predetermined position in the substantial absence of the diminution of the tensile properties thereof.

If is another object of the invention to provide a technique for the lateral positioning of a moving fibrous material which is particularly suited for use with a fibrous tape or ribbon consisting of a plurality of parallel adjoining multifilament fiber bundles.

It is a further object of the invention to provide a technique for the lateral positioning of a moving fibrous material which is particularly suited for use with inorganic fibrous materials which are highly susceptable to damage upon abrasive contact with a fixed guide.

SUMMARY OF THE INVENTION It has been found that an apparatus capable of laterally positioning at a relatively fixed location a continuous length of fibrous material comprising at least one multifilament fibrous bundle provided with a twist of at least about 0.1 tpi which is moving substantially in the direction of its length and which is also free to undergo lateral movement comprises:

supply means capable of providing the continuous length of moving fibrous material,

. takeup means capable of receiving the continuous length of fibrous material,

a rotatable roller intermediate the supply means and the takeup means having an axis of rotation substantially perpendicular to the continuous length of moving fibrous material and having its surface positioned to engage the continuous length of fibrous material,

d. variable drive means capable of rotating the rotatable roller,

e. a sensing means situated intermediate the supply means and the takeup means capable of continuously monitoring the lateral position of the continuous length of moving fibrous material, and

f. control means connecting the variable speed drive means and the sensing means capable of modifying the rotation of the rotatable roller in response to the lateral position of the continuous length of fibrous material as determined by the sensing means whereby the continuous length of moving fibrous material is substantially maintained at a fixed lateral location while in contact with the rotating roller.

It has been found that a process for laterally positioning at a relatively fixed location a continuous length of moving fibrous material comprises:

a. running substantially in the direction of its length a continuous length of fibrous material comprising at least one multifilament fibrous bundle provided with a twist of 'at least about 0.1 tpi which is free to undergo lateral movement,

b. sensing the lateral position of the continuous length of moving fibrous material relative to a predetermined position, and

c. controlling the rotation of a rotating roller which is in contact with the continuous length of moving fibrous material in response to the sensed position whereby the continuous length of moving fibrous material is substantially maintained at a fixed lateral position while in contact with the roller.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of an illustrative apparatus arrangement in accordance with the present invention wherein a tape consisting of a plurality of parallel adjoining twisted multifilament graphite bundles is passed through an optional surface treating oven and its lateral position precisely controlled prior to winding upon a flanged takeup bobbin.

FIG. 2 is a plan view illustrating the lateral displacement to the right of a ribbon consisting of six parallel adjoining Z-twisted multifilament graphite bundles while passing in contact with a counterclockwise rotating roller having a surface speed greater than that of the ribbon.

FIG. 3 is a plan view illustrating the lateral displacement to the left of a ribbon consisting of six parallel adjoining Z-twisted multifilament graphite bundles while passing in contact with a counterclockwise rotating roller having a surface speed less than that of the ribbon.

DESCRIPTION OF PREFERRED EMBODIMENTS The present invention is suitable for use in conjunction with a continuous length of fibrous material comprising at least one multifilament fibrous bundle provided with a twist of at least about 0.1 tpi.

The fibrous material may be of varied chemical composition. For instance, the fibrous material may be organic or inorganic in nature. Representative organic fibrous materials include the polymeric fibrous materials such as polyacrylics, polyolefins, polyesters, polyamides, polyimides, polyethers, etc. Stabilized or preoxidized acrylic fibrous materials may be efficiently processed in accordance withthe present invention. Representative inorganic fibrous materials include glass fibers, metal fibers, carbon fibers, etc. The present invention is particularly suited for use with continuous lengths of carbon fibers.

The terms carbon fibers or carbonaceous fibers are used herein in the generic sense and include graphite fibers as well as amorphous carbon fibers. Such fibers consist of at least 90 per cent carbon by weight (preferably at least 95 per cent carbon by weight), and are subject'to a diminution of single filament tensile properties upon contact with fixed guides. Graphite fibers are defined herein as fibers which consist essentially of carbon and have a predominant x-ray diffraction pattern characteristic of graphite. Amorphous carbon fibers, on the other hand, are defined as fibers in which the bulk of the fiber weight can be attributed to carbon and which exhibit an essentially amorphous x ray diffraction pattern. Graphite fibers generally have a higher Youngs modulus than do amorphous carbon fibers and in addition are more highly electrically and thermally conductive.

The multifilament fiber bundles may consist of staple fibers or of continuous filaments having a length substantially coextensive with that of the fiber bundle. The fiber bundles may accordingly assume the configuration of yarns, cords, strands, cables or similar fibrous assemblages. The continuous length of fibrous material utilized in the present invention is preferably a fiat tape or ribbon consisting of a plurality of parallel adjoining multifilament fiber bundles. Such tapes may comprise from 4 to 500 or more fiber bundles which are arranged in parallel. If desired, the tapes may optionally possess a weft pick interlaced therewith such as described in commonly assigned U.S. .Ser. No. 112,189, filed on Feb. 3, 1971 of K. S. Burns, G. R. Ferment, and R. C. Waugh entitled Improved Process for the Production of Carbonaceous Tapes which is herein incorporated by reference.

The fibrous bundles of the continuous length of fibrous material are provided with a twist of at least about 0.1 tpi, e.g. a twist of about 0.1 to tpi, and preferably a twist of about 0.25 to 2.5 tpi. The twist may be imparted to the same through the use of conventional techniques wherein the bundles are individually turned about a central axis. A relatively constant twist is provided throughout the fibrous bundle, which is commonly of either the S-type or the Z-type. A twist of the S-type is defined as a clockwise twist. A twist of the Z-type is defined as a counterclockwise twist.

The continuous length of fibrous material as heretofore described may be caused to move or run substanadvancing techniques. For instance, the fibrous material may be pulled from a supply source and continuously collected upon a rotating fiber takeup. Intermediate the supply source and the takeup may be situated one or more conventional driven or idler rollers which rotate at substantially the same surface speed as the continuous length of moving fibrous material. The continuous length of moving fibrous material may also undergo intermediate processing. The fibrous material is preferably under a moderate tension, and is moving in a horizontal plane with minimal contact being made with support or driving surfaces. The continuous length of moving fibrous material is free to undergo lateral movement and fixed guides designed to retard the lateral movement or displacement of the same are eliminated.

The lateral positioning of the continuous length of moving fibrous material is accomplished through contact (e.g. tangential contact) with a variably rotating roller situated intermediate the supply source and the fiber takeup. The rotating roller preferably has a diameter of at least 3 inches, e.g. 3 to 10 inches, thereby avoiding severe bending angles. The axis of rotation of the roller is substantially perpendicular to the length of moving fibrous material. While if is preferred that the roller be positioned at to the length of moving fibrous material, a slight skew in the roller may be tolerated. The extent of surface contact or engagement with the roller may be varied. In all instances, the fibrous material is in contact with the rotating roller for no more than one wrap (e.g. 10 to 90 per cent of the roller circumference). Commonly, the roller is so positioned that approximately 0.5 to 8 inches, and preferably 3 to 6 inches of its surface contacts or touches the length of moving fibrous material.

Intermediate the supply source and the fiber takeup, and preferably positioned adjacent the variably rotating roller, is provided a senser capable of continuously monitoring the lateral position of the continuous length of moving fibrous material. The senser has the ability to detect the edge of the continuous length of moving fibrous material relative to a predetermined position. The senser may be of a conventional type. Representative sensers include photoelectric cells, microswitches, electrical contacts, fluidic switches, etc. The preferred senser is a photoelectric cell.

A variable drive capable of rotating the roller at varying speeds in the direction of the fiber movement is attached to the variably rotating roller. The drive preferably is capable of rotating the roller at a surface speed from zero up to at least 2 times faster than that of the moving fibrous material. Provision can also be made for rotating the roller in the opposite direction to that of the moving fibrous material. Such rotation returns the yarn to the predetermined location more rapidly, but tends to abrade the same. A control element connects the variable drive and the senser which is capable of modifying the rotation of the variably rotating roller in response to lateral position of the continuous length of fibrous material as determined by the senser. As the variably rotating roller engages or contacts the moving twisted fibrous material, lateral movement may be imparted to same in the required degree so that the moving fibrous material is returned to a relatively fixed predetermined position. The moving fibrous material is thereby maintained at a relatively fixed lateral position while in contact with the roller. The tension upon the fibrous material while in contact with the roller is sufficient to obtain the desired interaction whereby the lateral movement of the same may be readily controlled. I

The lateral positioning of the continuous length of moving fibrous material is a function of l) the level of twist in the fibrous material, (2) the direction of the twist (e.g. a Z-twist or an S-twist), and (3) the speed of rotation of the roller relative to the speed of the moving fibrous material. For instance, the rotating roller will impart an opposite lateral movement to a Z-twisted fibrous material than to an S-twisted fibrous material.

The lateral positioning technique of the present invention may be utilized in those areas of fiber technology where moving lengths of twisted fibrous materials traverse an appreciable distance. The positioning technique is particularly suited for use in those areas where conventional fixed guides for retarding lateral movement have a deleterious influence on the fibrous material. Representative use areas include fiber coating operations, fiber surface modification operations, fiber drawing operations, and fiber thermal conversion or pyrolysis operations. The technique is particularly suited for use in conjunction with the formation of carbonaceous fibrous materials by the thermal treatment of a polymeric fibrous material or their after processing. a

The following example is given as a specific illustration of the invention. It should be understood, however, that the invention is not limited to the specific details set forth in the example. Reference is made in the example to the apparatus arrangement of FIG. 1.

The continuous length of fibrous material 1 is a flat ribbon having a width of 3 inches consisting of 300 parallel adjoining yarn bundles of a high strength-high modulus carbonaceous fibrous material provided with a uniform Z-twist of 0.5 tpi. The carbonaceous yarn bundles are derived from an acrylonitrile homopolymer yarn in accordance with procedures described in US. Ser. Nos. 749,957, filed Aug. 5, 1968, and 777,275, filed Nov. 20, 1968 (now abandoned). The twisted yarn bundles each consist of 400 continuous filaments having a total denier of about 400, a carbon content in excess of 99 per cent by weight, and exhibit a predominantly graphitic x-ray diffraction pattern.

The continuous length of fibrous material 1 is initially provided upon a flanged supply bobbin 2 which is free to rotate about a fixed axis 4. The fibrous material 1 is drawn from supply bobbin 2 through the rotation of a series of four driven parallel tensioning rollers 6. The

continuous length of fibrous material 1 is continuously wound upon flanged takeup bobbin 8 which is rotated about axis 10. As the fibrous material 1 continuously moves between flanged bobbins 2 and 8 at a rate of 12 inches per minute, it is free to undergo lateral movement. The continuous length of fibrous material is passed through an oven 12 which is provided with a surface modifying gas wherein it undergoes optional intermediate processing. A second series of four driven parallel tensioning rollers 14 maintain uniform tension upon the fibrous material during processing in oven 12.

The uniform winding of the continuous length of fibrous material 1 upon flanged bobbin 8 requires that the ribbon be precisely aligned as it passes between the parallel flanges of the same. Situated beneath the moving ribbon and in contact therewith is rotating roller 16 having a diameter of 6 inches. The moving tape 1 is in contact with the surface of rotating roller 16 over approximately 5 inches of its surface. A photoelectric cell 18 which is capable of continuously monitoring the lateral position of the ribbon 1 is situated adjacent the rotating roller 16. A beam of light is directed downwardly within the photoelectric cell 18, and continuously senses the position of the edge of the moving ribbon 1. The moving ribbon depending upon its lateral position may block none, all, or a portion of the light at a given time. When the ribbon 1 is precisely aligned at the desired position, approximately one-half of the light is blocked within the photoelectric cell 18.

A variable speed motor 20 is attached to rotating roller 16 via chain drive 22 which is capable of rotating the roller 16 at varying speeds in the same direction the fibrous material 1 is moving. Control element 24 connects motor 20 to photoelectric cell 18, and is capable of modifying the rotation of roller 16 in response to the lateral position of the ribbon 1 as determined by photoelectric cell 18 whereby the ribbon 1' is substantially maintained at a fixed predetermined location while in contact with the surface of rotating roller 16 and thereby proper alignment for takeup on flanged bobbin 8 is facilitated. Control element 24 is a phase shift type motor control comprising a triac switch wherein the quantity of light passing through the photoelectric cell 18 controls the amount of voltage supplied to the gate of the triac switch.

FIG. 2 illustrates the lateral displacement to the right of a moving ribbon 30 consisting of six parallel adjoining Z-twisted multifilament graphite bundles while passing in contact with a counterclockwise rotating roller 32 wherein the roller has a greater surface speed than that of the ribbon. Each graphite bundle is twisted uniformly at 0.5 tpi. The ribbon3l] is moving at a rate of 12 inches per minute in the direction indicated by the arrow. The roller 32 is rotating at a surface speed of 14 inches per minute.

FIG. 3 illustrates the lateral displacement to the left of a moving ribbon 40 consisting of six parallel adjoining Z-twisted graphite bundles while passing in contact with a counterclockwise rotating roller 42 wherein the roller has a lesser surface speed than that of the ribbon. Each graphite bundle is twisted uniformly at 0.5 tpi. The tape 40 is moving at a rate of 12 inches per minute in the direction indicated by the arrow. The roller 42 is rotating at a surface speed of 10 inches per minute.

Although the invention has been described with preferred embodiments, it is to be understood that variations and modifications may be resorted to as will be apparent to those skilled in the art. Such variations and modifications are to be considered within the purview and scope of the claims appended hereto.

I claim:

1. An apparatus capable of laterally positioning at a relatively fixed location a continuous length of fibrous material which is moving substantially in the direction of its length and is also free to undergo lateral movement wherein said continuous length of fibrous material Comprises at least one multifilament fibrous bundle provided with a twist of at least about 0.1 tpi, said apparatus comprising:

a. supply means capable of providing said continuous length of moving fibrous material,

b. takeup means capable of receiving said continuous length of fibrous material,

c. a rotatable roller intermediate said supply means and said takeup means having an axis of rotation substantially perpendicular to said continuous length of moving fibrous material and having its surface positioned to engage said continuous length of fibrous material,

d. variable drive means capable of rotating said rotatable roller,

e. a sensing means situated intermediate said supply means and said takeup means capable of continuously monitoring the lateral position of said continuous length of moving fibrous material, and

, f. control means connecting said variable speed drive means and said sensing means capable of modifying the rotation of said rotatable roller in'response to the lateral position of said continuous length of fibrous material as determined by said sensing means whereby said continuous length of moving fibrous material is substantially maintained at a fixed lateral location while in contact with said rotating roller.

2. An apparatus in accordance with claim 1 wherein said takeup means is a flanged bobbin.

3. An apparatus in accordance with claim 1 wherein said sensing means is a photoelectric cell.

4. An apparatus in accordance with claim 1 wherein said sensing means is situated adjacent said rotatable roller.

5. An apparatus in accordance with claim 1 wherein said rotatable roller has a diameter of about 3 to inches.

6. A process for laterally positioning at a relatively fixed location a continuous length of moving fibrous material comprising:

a. running substantially in the direction of its length a continuous length of fibrous material comprising at least one multifilament fibrous bundle provided with a twist of at least about 0.1 tpi which is free to undergo lateral movement,

b. sensing the lateral position of said continuous length of moving fibrous material relative to a predetermined position, and

c. controlling the rotation of a rotating roller which is in contact with said continuous length of moving fibrous material in response to said sensed position whereby said continuous length of moving fibrous material is substantially maintained at a fixed lateral position while in contact with said roller.

7. A process for laterally positioning a continuous length of moving fibrous material in accordance with claim 6 wherein said continuous length of moving fibrous material comprises a plurality of parallel adjoining multifilament fibrous bundles in the form of a flat ribbon.

8. A process for laterally positioning a continuous length of moving fibrous material in accordance with claim 6 wherein said multifilament fibrous bundle is provided with a twist of about 0. l to l( tpi.

9. A process for laterally positioning a continuous length of moving fibrous material in accordance with claim 6 wherein said multifilament fibrous bundle is provided with a twist of about 0.25 to 2.5 tpi.

10. A process for laterally positioning a continuous length of moving fibrous material in accordance with claim 6 wherein said multifilament fibrous material is a carbonaceous fibrous material containing at least about per cent carbon by weight. 

1. An apparatus capable of laterally positioning at a relatively fixed location a continuous length of fibrous material which is moving substantially in the direction of its length and is also free to undergo lateral movement wherein said continuous length of fibrous material comprises at least one multifilament fibrous bundle provided with a twist of at least about 0.1 tpi, said apparatus comprising: a. supply means capable of providing said continuous length of moving fibrous material, b. takeup means capable of receiving said continuous length of fibrous material, c. a rotatable roller intermediate said supply means and said takeup means having an axis of rotation substantially perpendicular to said continuous length of moving fibrous material and having its surface positioned to engage said continuous length of fibrous material, d. variable drive means capable of rotating said rotatable roller, e. a sensing means situated intermediate said supply means and said takeup means capable of continuously monitoring the lateral position of said continuous length of moving fibrous material, and f. control means connecting said variable speed drive means and said sensing means capable of modifying the rotation of said rotatable roller in response to the lateral position of said continuous length of fibrous material as determined by said sensing means whereby said continuous length of moving fibrous material is substantially maintained at a fixed lateral location while in contact with said rotating roller.
 2. An apparatus in accordance with claim 1 wherein said takeup means is a flanged bobbin.
 3. An apparatus in accordance with claim 1 wherein said sensing means is a photoelectric cell.
 4. An apparatus in accordance with claim 1 wherein said sensing means is situated adjacent said rotatable roller.
 5. An apparatus in accordance with claim 1 wherein said rotatable roller has a diameter of about 3 to 10 inches.
 6. A process for laterally positioning at a relatively fixed location a continuous length of moving fibrous material comprising: a. running substantially in the direction of its length a continuous length of fibrous material comprising at least one multifilament fibrous bundle provided with a twist of at least about 0.1 tpi which is free to undergo lateral movement, b. sensing the lateral position of said continuous length of moving fibrous material relative to a predetermined position, and c. controlling the rotation of a rotating roller which is in contact with said continuous length of moving fibrous material in response to said sensed position whereby said continuous length of moving fibrous material is substantially maintained at a fixed lateral position while in contact with said roller.
 7. A process for laterally positioning a continuous length of moving fibrous material in accordance with claim 6 wherein said continuous length of moving fibrous material comprises a plurality of parallel adjoining multifilament fibrous bundles in the form of a flat ribbon.
 8. A process For laterally positioning a continuous length of moving fibrous material in accordance with claim 6 wherein said multifilament fibrous bundle is provided with a twist of about 0.1 to 10 tpi.
 9. A process for laterally positioning a continuous length of moving fibrous material in accordance with claim 6 wherein said multifilament fibrous bundle is provided with a twist of about 0.25 to 2.5 tpi.
 10. A process for laterally positioning a continuous length of moving fibrous material in accordance with claim 6 wherein said multifilament fibrous material is a carbonaceous fibrous material containing at least about 90 per cent carbon by weight. 